ABO blood group influences a candidate's likelihood of receiving an HLA zero antigen mismatch kidney.

National sharing of HLA zero-mismatched kidneys has improved long-term graft survival. The distribution of those HLA-matched kidneys by ABO blood group, however, has not been examined. Utilizing the UNOS/OPTN (United Network for Organ Sharing/Organ Procurement Transplantation Network) database, we analysed 112 971 kidney waiting list registrations added during 6/3/95-31/12/00, and 8162 HLA zero-mismatched (0 mm) primary kidney transplants in the USA during 1/1/88-31/3/02. We also analyzed A isoagglutinin titer histories for 87 blood group B end stage renal disease (ESRD) patients for whom at least 1 yr of testing was done. Blood group A patients received 40.1% of the HLA-0 mm kidneys while having a 26.5% representation on the national waiting list. Blood group B patients comprised 17.4% of the waiting list, but received only 10.4% of the HLA-0 mm kidneys. Most (89.6%) blood group B patients awaiting kidney transplantation have low levels of A isoagglutinins, making them eligible to receive a blood group A(2) kidney transplant. The national HLA-0 mm kidney allocation sharing system's imbalance by ABO blood group could be partially resolved in the future by allocating HLA-0 mm blood group A(2) kidneys to B patients.